Of course, I'm assuming the two pickups are on diagonally-opposite corners. Long story short: with the right combination of accelerations, you can easily cavitate on 3 gallons - maybe even 6 gallons, with just two pickups. You really need 4.00000000000000 pickups.

So there is a substantial baffle running driver side to pass side not quite halfway to the front from the filler side and the bottom of the tank is slanted slightly toward the front. The baffle and the slope of the tank are going to work hard to keep what fuel is left in the front half of the tank. The two pickups are just in front of that baffle on each side pretty close to the outside edges of the tank.

You can see the ridge in the tank in this picture where the side to side baffle is.

And in this picture you can see the baffle and the position of the corner pickup.

I'm pretty sure it'll be just fine. If for some strange reason it does starve, adding more pickups won't be that big of a deal.

I’m in disagreement with both of you. You need a baffled sump in all four corners.... lol

Those F.I GN tanks with a stick pump and a bucket will not starve either. I have had one heck of a time draining the gas out of those with the top of the tank cut open. The plastic bucket is way better than most would think. It’s not a regular muscle car tank.

Hopefully I can get my SS back on the project list one day and run Barney. I would like to see with only my years of dirt track racing experience. If I can compete with a professionally schooled race car driver and a Ron Sutton consulted chassis. Maybe all that speed tech stuff I bought might give me a chance? But I doubt it, my car is only eye candy! 😛

What this amounts to is that if you accelerate/decelerate hard in a direction perpendicular to an axis running through your two existing pickups, you are no better protected against cavitation than you would be with a single, fixed, central pickup with all the baffling you've got. Here's a simple test to prove this, since it's a bit hard to explain the background theory:

1. Get a Tupperware tub with the same proportions as the gas tank (roughly 1:4:4). 2. Place two clear marking in the bottom of the tub where your pickups are. 3. Fill tub with water to roughly 1/3 capacity (= 6 gallons of gas). 4. Tilt tub to about 45 deg off the horizontal, which is a static simulation of 1-g dynamic acceleration. 5. Holding the tub at this inclination, simultaneously rotate the tub through a full 360 deg around a vertical axis, and watch when both markings get uncovered by water. When that happens, you've got pump cavitation in real life. Also, the cavitation will get worse as the gas (water for Tupperware) level drops, just as we expect in real life. The Tupperware experiment just allows you to see it more clearly.

Of course, baffling slows the rate at which gas will shift, but it's not an if, but a when, when cavitation happens.

HTH,MAP

PS: 1 SlowSS: All this isn't to say I doubt you one bit. It's just that with Lance approaching an amazing 1.2g of horizontal acceleration, he's unusually prone to cavitation to where conventional solutions are less likely to work.

Regarding the fuel tank, I appreciate everyone's feedback. Trust me when I say that I've agonized over this part of the build for more than 3 years.

What finally led me to making the choice I did was speaking with a lot of owner\drivers of old EFI converted muscle cars that drive them like I drive mine about what they like and\or dislike about their fuel systems. Theories and opinions about what may or may not work the best are great to type about on the internet, but actual experience with said products from those that own and use them like I intend to is my preferred route to take when upgrading a part. I then like to test them myself and adjust accordingly.

Just look at the 14 different sway bars I've had on this car so far for an example...

I'm confident this fuel tank was the right move for me. If it for some reason disappoints, making it better will not be that difficult. For those that think I spent too much time, money or effort building this tank...just think back to the time I relocated the lower control arm mounts in the frame...and how that turned out. Y'all thought I was crazy back then as well.

Years ago when teaching the topic of accuracy and precision in freshman physics, I'd give the hypothetical case of a 3,500lb car that accelerated from 0-60 in 6.0 sec. I'd ask the students, assuming we change nothing except to add 0.10 lb of mass to the car, how much longer should it take to reach 60mph? Do we trust a measurement, or do we trust a calculation?

After the inevitable student in the class who would say 6.0 sec was slow (even back then!) almost no one ever got the correct answer, which was the calculation. Why? Because the noise of the measurement limited its resolution, and the certainty of Newton's second law was beyond question (then and now.) Likewise here: the physics of what I discussed is unassailable, but the certainty of not creating an unacceptable outcome, or even just detecting it, is relatively poor.

Having said that, with two pickups, Lance, indeed you may never, ever get cavitation. Where I'm left scratching my head is why you worked so hard to install two pickups, when they offer no advantage whatsoever over a single pickup, in a direction of acceleration perpendicular to an axis passing through both pickups.

Ultimately it all comes down to your tolerance for risk. (This is absolutely your call to make btw; just trying to help!)

Where I'm left scratching my head is why you worked so hard to install two pickups, when they offer no advantage whatsoever over a single pickup, in a direction of acceleration perpendicular to an axis passing through both pickups.

There is a solid baffle directly behind both pickups on each side, whereas the center of the tank (where a stock or single pickup is located) the baffle is open to the rear portion of the tank to let fuel into (and out of) the front compartment easier\quicker.

I would argue that on an acceleration only situation, the baffle would keep one or both corner pickups covered with fuel whereas the single center pickup would have a better chance of being uncovered due to the opening in the baffle allowing the fuel to rush to rear of tank.

This is the driver side pickup which is almost exactly in the center (front to rear) of the bottom of the tank.

This is the passenger side pickup

Rearward of the baffle is where the bottom of the tank slopes up toward the filler neck.

That bead in the baffle is about 1.5" up from the bottom of a 8" deep tank at that point. On a sitting still, level situation, the pickups would be covered with less than a 1/2" of fuel in the bottom of the flat part of the tank. I would guess that to take less than a half gallon of fuel but I'm not mathematician. That flat portion of the tank bottom is approx 32" x 10" if anyone else wants to do the math.

If you accelerate forward with that half gallon of fuel in the bottom, the baffle will keep the fuel from climbing up the back sloped half of the bottom of the tank and keep the pickups covered (probably until the fuel in the center portion of the tank has all gone through the baffle and the fuel from each side follows). Granted, a tank with a rear bottom sump would be much better for a drag race suited car that wanted to draw small amounts of fuel from the tank under hard acceleration...but those tanks are worthless to anyone that corners with their car...I've watched that happen in person.

I guess in a worst case scenario of really wanting to draw every last ounce of fuel out a tank, having pickups in the rearward corners of the tank bottom would help...but frankly I'm not sure how one would even get back there to attach them to the tank floor with the baffle in the way. It was difficult enough getting access to the floor on the front side of the baffle to weld these tabs in place.

In a cornering situation, I have zero doubts the two corner pickup setup we used will have any trouble keeping the pickups covered...with a 1/4 tank of fuel or a little less (3-4 gallons)...which was my main concern. The guys I know with a pump on a stick, baffled setup like a GN tank fuel starve with anything less than a half tank of fuel (7.5 gallons).

Now in a hard braking situation, with a small fuel load...I could see the 2 pickups being uncovered. Thankfully you are typically off the throttle and the injectors are closed under braking so the pickups won't need to do their job until the injectors are opened back up again. I suspect the first fuel starve I'll see when I run the tank way down will be after a hard braking and a quick jab back to the throttle. Usually that involves a turn as well so that 1-2 gallons of fuel will go to one side of the tank or the other and might even cover the pickup up regardless. I guess we'll see.

Sorry to take so long to answer. Those two views were a bit confusing to me; I now realize the first picture was taken from the perspective of the center looking toward the driver's side, and the second from the same vantage point, looking toward the passenger's side. It seems obvious in the telling, but the non-square shape of the tank led to an initially confusing interpretation of what was being seen.

Anyway, it's still true that two pickups will have the same effect as one when exposed to an acceleration perpendicular to an axis joining the two. In your case, that vulnerable orientation is front-rear. As you say, braking should be safe since fuel demand is extremely low. But acceleration from engine output is much more vulnerable. I'm guessing your car is peaking in the vicinity of 0.7-0.8g. Steady state, this would cause the gas surface to rise 35 deg from the horizontal in a partially-full state. For visualization, think of, or better try, the Tupperware experiment.

Baffling does nothing to influence the final distribution of gas in the tank. It only influences the rate of change of distribution, and tends to dampen sloshing. If the baffling biases flow in one area over another, then the gradient of that rate of change will be influenced by that bias. When I spoke of four versus two pickups, I couldn't address that aspect because it was unknown to me. But it doesn't alter the underlying principle.

So again, your solution may indeed allow you never to experience cavitation. Then again, it may not. On the other hand, four pickups, with one in each corner, would completely guarantee that outcome. As I said before, it all comes down to your tolerance of risk.

Zooming-out to the bigger picture, I just want to say again that I'm not trying to argue; I'm just trying to help! Hopefully the information I provided here will help a bit.

So I spent some time in the shop as well today, finally finished up all the wiring. I'm not fast at it, nor the most neat and tidy at it, but I'm pretty sure the connections are all good and it all should work as designed when I llight it off. **Fingers Crossed** I'm pretty happy with how the relay\fuse box worked out and where everything landed.

Here are the all new battery connections. The power to the ECU and engine harness are on the side post mounts, everything else is now powered and grounded through the top posts.

I ran new 2 ga wire to the starter and 6 ga wire to the Alt and engine ground. It's what I had laying around and I needed to extend them anyway to move them to the top posts. Also ran 10 ga from there to the positive and negative distribution blocks on front side of core support and to the body bolt on the fender.

Looking down behind the headlight in front of core support, you can see the relay\fuse box and the Positive distribution block on the radiator duct.

Better look at the ground block.

I struggled with making the leads short enough to be tidy but leaving them long enough to pull the box up out of the hole should I ever need to service anything on it. As it ended up I can just get it up on top of the cowl without having to unhook any wires. Once I'm sure everything works I'll tie some looms up to make sure they stay put.

View up at the bottom of the box...

This was taken before I had the box bolted down and the main leads finished.

I still have to do a bit of work under the dash, the wire from coil needs to be hooked to gauge module for the tach and the wires to fan switch are going to get shortened and cleaned up. Other than that though, I'm DONE with wires...

Just need to make up four fuel line connections, run the fuel line and filter...and put the tank back in and I'll be ready to fire it off for the first time. Unfortunately an impromptu trip out of town early next week will delay this until after we return. Glad I got time to get the wiring down before we left though.

A little confused, the battery swapped sides? And the relay box location is where the bat was?

This should help clear up the confusion...

I decided that the 10 AWG wire probably wasn't suitable for the Battery Positive to Positive Distribution block, so I picked up a 24" piece of 6 AWG to use there instead. That's the same size as what I have coming from the Alternator to Battery so should be plenty.

I might get a chance to throw some fuses and relays in it today and do a little testing to make sure it all fires off as it should before I leave town for a week. I'll have 911 on speed dial just in case...

I'm not going to sugar coat it...had a couple of pretty frustrating days in the shop.

I finished up putting the hose ends on the lines Friday and actually got pretty good at it by the end.

This "third hand" I picked up really helped with the process

Wish putting the tank in went as smooth. My guess is the new replacement tank is a smidge larger than the OEM tank and I struggled getting the old straps around the tank and installed. What should have taken about 15 minutes took a couple hours. Then I had to run the fuel line and my desire to make it as fit and finish as OEM led to more frustration. Between being larger diameter and stiff...I had a fight on my hands, but I got it done. I quit for the day and decided to wait until I was fresh Sunday morning to fire up the pump and test for leaks. Good thing I did...

Had the wife in the car to turn the key while I had the throttle body end of the line pointed toward a container so I could rinse the lines out before connecting to the throttle body. I had blown the lines and filter out but didn't want any trash from the pump getting into the injectors. She turned the key...nothing...

Sent her on her way and I started to chase down why. I'll save you from the horrid details but just know it wasn't until the fuel pump was back out on the bench (yes I had to drop the tank again to get it out), had jumper cables on the pins and a battery charger set at 20 amps powering them...that it finally decided to come to life. I then slowly reinstalled everything while testing the pump operation each step of the way. Once pump was back in the tank and tank raised up to installed location and all connections made, I hot wired the pump at the relay and I had fuel coming out the throttle body end of the line...and out from under the car... Seems I should have put a wrench on the inline filter housing itself to make sure the end cap of it was snugged down. Once that mess was cleaned up and line connected to throttle body again, I tested it again and NONE of my hose ends leaked... Woo Hoo! I cleaned up, aired the shop out and went in the house for a shower and a rest while the battery charged back up.

I just now returned in from the shop where I sat down in the driver seat and configured the handheld with my engine specs and uploaded the file to the ECU. I then did the TPS autoset and verified that all sensors are operational. The final screen said we are now ready to start the engine!!!

Well, kinda... I still have to fill cooling system and tighten the belts... THEN we'll be ready to fire it off.